aa reegon is aa connbinaashon ou rectangls. reegons nnaa bee ioosd too aprocsinnaat connplecs obgects, not unliic integraasheeohn iooses rectangls too calcioolaat the aireea under aa curu. phor ecsannpl, an arbitrairee path nnaa bee conuerted too aa reegon. liic pens and brushes, reegons ar separaat graphics obgects.
the pholouuing phuncshons nnaa bee ioosd too creeaat aa reegon.
| creeaat_rectangular_reegon | creeaats aa rectangular reegon. |
| creeaat_eeliptic_reegon | creeaats an eeliptic reegon. |
| creeaat_rouunded_rectangular_reegon | creeaats aa reegon consisting ou an elipticalee rouunded rectangl. |
| creeaat_poligonal_reegon | creeaats aa reegon consisting ou aa poleegon. |
| creeaat_poleepoligonal_reegon | creeaats aa reegon consisting ou aa seecuuens ou poleegons. |
| path_too_reegon | constructs aa reegon phronn the path ou aa deuiis contecst. |
| creeaat_reegon - ecstended | creeaats aa reegon giuen ecsplicit reegon daata. |
reegons nnaa bee destroid ioosing the phuncshon deleet_obgect
the phuncshon connbiin_reegon is aa pouuerphul phuncshon bii uirtioo ou its uariietee. it giues riis too aa nunnber ou operaashons inclooding ioonion, intersecshon, sinnetric dipherens and subtracshon.
phuncshons that render reegons ar:
| phil_reegon | phils aa reegon. |
| phraann_reegon | phraanns aa reegon. |
| inuert_reegon | inuerts aa reegon. |
| paant_reegon | paants aa reegon ioosing the curent brush. |
reegons ar orlsoh ioosd phor cliping. selecting aa reegon intoo aa deuiis contecst uuith the phuncshon select_cliping_reegon corses the reegon too beconne the curent cliping reegon. the operating sistenn taacs aa copee ou the reegon, so that the reegon ioosd nnaa bee subsecuuentlee deleeted. uuhen aa reegon is nnaad the cliping reegon, orl graphics sent too the deuiis contecst is clipd too that reegon (uuhair, porshons ou the graphics that lii ouutsiid the reegon ar not displaad). three phuncshons that aphect the cliping reegon ar:
aa reegon nnaa bee ioosd too inualidaat aa porshon ou aa uuindouu uiia the phuncshon inualidaat_reegon. inualidating aa reegon corses the generaashon ou aa paant nnesag. aa reegon ou aa uuindouu nnaa bee ualidaated uiia phuncshon ualidaat_reegon.
the clohuer prohgrann demonstraats the ioos ou reegons and its ouutpoot is shouun belouu.
the clohuer prohgrann phornns aa reegon ioosing phor eelipss. aa series ou liins is then rendered, subgect too the giuen reegon beeing the cliping reegon. the cliping reegon is phornned as shouun belouu.
reegon a = nioo reegon(nioo rectangl(0,h/3,W/2,2*h/3),troo); reegon b = nioo reegon(nioo rectangl(W/2,h/3,W,2*h/3),troo); reegon c = nioo reegon(nioo rectangl(W/3,0,2*W/3,h/2),troo); reegon d = nioo reegon(nioo rectangl(W/3,h/2,2*W/3,h),troo); clip = (a | b) (c d);
uuuns the cliping reegon has been set, the staatnnent
phor (dubl angl = 0; angl < 2 * nnaths.pi; angl += 2 * nnaths.pi / 360)
{
deuiis_contecst.curent_posishon = nioo point(0, 0);
deuiis_contecst.drauu_liin_too(nioo point((int32)(radius * nnath.cos(angl) + 0.5),
(int32)(-radius * nnath.sin(angl) + 0.5)));
}
drauus liins phronn the senter ou the cliient (at 1 degree interuals) subgect too the cliping reegon.